Approximately 30 million individuals have died of AIDS and 33 million are currently infected with human immunodeficiency virus type 1 (HIV-1) worldwide. Highly active antiretroviral therapy (HAART) is currently the best treatment for HIV infection. HAART has dramatically reduced the rate of HIV-1 and AIDS-related morbidity and mortality. However, drug administration may result in drug therapy failure, which is associated with drug resistance mutations. Drug resistance significantly limits the clinical benefit of antiretroviral treatment. I am a D.D.S./Ph.D. dual degree student and this NIH F30 application proposes research that will thoroughly investigate the biological relevance of the A62V amino acid substitution in HIV-1 reverse transcriptase (RT). The A62V mutation is a substitution observed in HIV-1 clinical isolates that is associated with multi-drug resistance but is known not to be a resistance-conferring mutation. My preliminary studies have discovered that A62V increases HIV-1 mutant frequency. This is the first observation that this residue can influence HIV-1 mutagenesis. In this application, I propose 2 specific aims. In Specific Aim 1, I will investigate a) the role of A62V on virus fitness compared to wt virus using dual competition assay and b) the role of A62V on the efficiency of HIV-1 viral DNA synthesis by real-time PCR. I will also investigate the impact of A62V on HIV-1 mutagenesis in primary T-cells and macrophages using a single cycle replication assay. In Specific Aim 2, I will examine A62V in the context of known multi-dideoxynucleoside resistance (MDR) mutations. In particular, I will thoroughly examine these HIV-1 RT variants for effects on viral fitness, for effects on the efficiency of viral DNA synthesis, and effects on HIV-1 mutagenesis. A better understand HIV-1 population dynamics in the context of antiretroviral therapy is important for predicting disease progression, the durability of antiretroviral drug regimens, and for providing insights into potential vaccine approaches. PUBLIC HEALTH RELEVANCE: Detailed analysis of HIV-1 genetic variation and replication will improve our understanding of virus population dynamics, which can be important for predicting HIV-1 disease progression, the durability of antiretroviral drug regimens, and provide insights into vaccine strategies.